Behaviour and habits Sunda pig-tailed macaques live in groups consisting of (many) more adult females than males. They spend most of the day up in the trees and are only on the ground for about eight per cent of their life. Male hierarchy is determined differently to females. Physical strength determines the rank in males; the stronger the male, the higher the rank. For females, it is all about the family line. The daughters of females with a high rank will automatically also receive a high rank. Sunda pig-tailed macaques occasionally come close to human habitats. During heavy rain storms, Sunda pig-tailed macaques like to steal crops while the farmers are sheltering from the rain. When it’s not raining, the monkeys have to be more careful. One by one they sneak into the crop field to try and steal some food. One monkey, often a young adult male, is always on the lookout to sound the alarm when people are near.